Males are more commonly affected than females. It is also associated with first born males about four times as often, although there exist many more first borns in the poplulation.
Babies with this condition usually present any time in the first weeks to months of life with progressively worsening vomiting. The vomiting is often described as non-bile stained ("non bilious") and "projectile vomiting", because it is more forceful than the usual spittiness (gastro-oesophageal reflux) seen at this age. Some infants present with poor feeding and weight loss, but others demonstrate normal weight gain. Dehydration also can occur causing the baby to cry without having tears, and having less wet or dirty nappies such as going hours or a couple days without having anything.Constant hunger, belching, and colic are other possible signs as the baby is not able to eat properly.
Most cases of pyloric stenosis are diagnosed/confirmed with ultrasound, if available, showing the thickened pylorus.
The definitive treatment of pyloric stenosis is with surgical pyloromyotomy known as Ramstedt's procedure (dividing the muscle of the pylorus to open up the gastric outlet). This is a relatively straightforward surgery that can possibly be done through a single incision (usually 3–4 cm long) or laparoscopically (through several tiny incisions), depending on the surgeon's experience and preference.